Blood pump supported by passive magnetic forces

ABSTRACT

A blood pump may be provided that includes an inlet, an outlet and a rotor for delivering fluid from the inlet to the outlet, wherein the rotor is suspended within the blood pump by radial passive magnetic forces and axially is preloaded in one direction at least by way of passive magnetic forces so that, during a fluid-delivering rotation of the rotor, the axial thrust of the rotor acts counter to the magnetic attraction acting axially in the direction of the outlet.

CROSS-REFERENCE TO RELATED APPLICATIONS

This application is a continuation of U.S. patent application Ser. No.16/075,557, which is a 371 nationalization of international patentapplication PCT/EP2017/052549 filed Feb. 6, 2017, which claims priorityunder 35 USC § 119 to European patent application 16191579.8, filed Sep.29, 2016 and German patent application DE 10 2016 001 289.7, filed Feb.5, 2016. The entire contents of each of the above-identifiedapplications are hereby incorporated by reference.

TECHNICAL FIELD

The present property right relates to a blood pump.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 shows a cross-section of a bearing having a magnet configurationthat enables a radial passive magnetic force and preloading in the axialdirection;

FIG. 2 shows an example of a blood pump that comprises an additionalmechanical bearing in the outlet-side region of the rotor;

FIG. 3 shows a further example of a blood pump that comprises ahydrodynamic bearing in the outlet-side region of the rotor;

FIG. 4 shows a further example of a blood pump that comprises amechanical bearing in the outlet-side region of the rotor;

FIG. 5a shows a side view of a radial pump;

FIG. 5b shows a section B-B from FIG. 5 a;

FIG. 5c shows a section C-C from FIG. 5 a;

FIG. 5d shows a scaled down perspective view of the pump shown in FIG. 5a;

FIG. 6a shows a side view of a radial pump;

FIG. 6b shows a section B-B from FIG. 6 a;

FIG. 6c shows a second C-C from FIG. 6 a;

FIG. 6d shows a scaled down perspective view of the pump shown in FIG.6a ; (FIG. 6a showing a side view, FIG. 6b showing a section B-B fromFIG. 6a , FIG. 6c showing a section C-C from FIG. 6a , and FIG. 6dshowing a scaled down perspective view of the overall pump;

FIG. 7 shows a cross section of an example of a blood pump in which anaxial inlet and a radial outlet are provided; and

FIG. 8 shows a further schematic illustration of a pump according to thepresent application.

DETAILED DESCRIPTION

One important property of modern blood pumps is the degree of blooddamage. Depending on the pump concept, and in particular the bearingconcept, varying degrees of blood damage can occur. On the one hand, aslittle blood damage as possible is desirable, for example byimplementing shapes that favor flow to as great an extent as possible,large gap dimensions and the like. On the other hand, the size of thepump should be limited, in particular in the case of fully implantablepumps. Furthermore, it is desirable to minimize the size of the controlunit designed for speed control and for bearing control to as great anextent as possible, while also keeping the related power consumptionlow.

At present, different bearing types exist for clinically used rotaryblood pumps:

-   1. Mechanical bearings (commercial examples: Heartmate II, Reliant    Heart)-   2. Hydrodynamic bearings (commercial product: Ventrassist)-   3. Hybrid bearings (hydrodynamic and passive magnetic, commercial    examples: HVAD, MVAD)-   4. Active magnetic bearings (in one or more directions) (commercial    examples: INCOR, HM III).

All present bearing configurations have advantages and disadvantages.While the active magnetic bearing, for example, in theory is ideal withrespect to blood damage, it is often complex to implement (for exampleas it relates to the control unit and the power consumption) andassociated with additional heat input and/or with substantial secondaryflows. On the other hand, hydrodynamic/hybrid bearings are completelypassive, which allows a small control unit to be installed and enableslow power consumption. The hemocompatibility (or blood damage) of thesesystems, however, is not necessarily advantageous in terms of theirtechnology due to the very small gap sizes that are present across largeareas and is also difficult to implement, especially in the case ofaxial pumps.

Proceeding from this prior art, it is the object of the present propertyright to provide a blood pump that not only has a small andenergy-saving design, but also causes very low blood damage.

This initially involves a blood pump, comprising an inlet, an outlet anda rotor for delivering fluid, in particular blood, from the inlet to theoutlet, wherein the rotor is suspended inside the blood pump by way ofradial passive magnetic forces and is, at least passively, repelled orattracted axially in one direction. The blood pump, for example, isconfigured in such a way that, during a fluid-delivering rotation of therotor, the axial thrust of the rotor acts counter to the magneticattraction acting axially in the direction of the outlet.

In this way, a very advantageous passive system is provided with respectto the control unit and the corresponding power consumption as well asthe small size of the corresponding components. The rotor is drawn inthe direction of the inlet by the axial thrust created by rotorscomprising blades or helices or other delivery elements. This force actscounter to the axial passive magnetic force acting purely magnetically.This reduces the load acting on a mechanical bearing, so that the rotoris suspended without forces to as great an extent as possible, andideally even “levitated.” As an alternative, the level of the magneticpreload can be selected in such a way that the mechanical contactbetween the rotor and the stator is preserved in all conceivablescenarios.

The rotor for example is driven in a contact-free manner by a brushlessdirect current motor.

According to one refinement, the contact-free portion of the suspensionof the rotor takes place exclusively by way of a passive magneticforces, which is to say that no additional control coils and the likeare required for positioning the rotor. As an alternative, however, itis possible to provide an electromagnetic and/or electrodynamic deviceacting on the rotor, for example so as to enhance the axial thrust ofthe rotor (which is to say, counter to the delivery direction of thefluid, for example). This can be done, for example, to further reducethe load on the mechanical bearing so as to hold the rotor in alevitating or low-force manner to as great an extent as possible. Thismay be achieved, for example, by way of appropriate electromagneticdevices or control coils.

According to one refinement, the rotor is additionally supported by amechanical bearing, in particular for axial support. This mechanicalbearing can, in particular, be designed as a contact bearing, and inparticular as a tip bearing or ball bearing. This creates a mechanicallyreliable device, which ensures a stable rotor position, in particularalso at low speeds.

As an alternative or in addition, in particular for axial support, therotor may be additionally supported by a hydrodynamic bearing, which,for example, is also arranged in the outlet-side region of the rotor.Advantageous examples are hydrodynamic bearings in the form of spiralgroove bearings.

According to one refinement, an additional bearing, and in particular anaxial catcher bearing, is provided for limiting the axial rotormovement. This ensures that the rotor blades or blood contact surfacesof the pump are not damaged as a result of the rotor being drawnexcessively in the direction of the inlet during “suctioning” of thepump on a cardiac wall and the attendant high axial thrust.

According to one refinement, the rotor and/or abutting parts of theblood pump are reinforced in the region of at least one additionalbearing, in particular with ceramic materials and/or a hard coating,such as diamond-like carbon (DLC).

Blood pumps described above may be used for a variety of bearingconcepts, for example for axial pumps/semi-axial pumps (mixed flowpumps) or radial pumps. For example, axial inflow and delivery make takeplace through the rotor, and axial outflow or tangential outflow maytake place in the region of the outlet. All concepts have in common thatboth the inlet and the outlet can be connected to human or animal bloodvessels so as to enhance and/or regulate the natural blood flow.

Further aspects of the present invention will be described hereafter byway of example.

According to one embodiment of a blood pump according to the invention,the blood pump is a pump that can be fully implanted in a human oranimal body. This is preferably a pump that is suitable for enhancingand/or regulating the blood circulation of the body.

Preferably, the inlet of the pump has an axial design with respect to anaxis of rotation of the rotor, the outlet has a radial design withrespect to the axis of rotation of the rotor, and/or the rotor of theblood pump has an axial, semi-axial or radial design. In this way, it ispossible to easily and reliably support and stabilize different types ofrotors.

According to a further embodiment, bearing magnets of the rotor areprovided so as to stabilize the rotor radially and axially inside thehousing of the blood pump. This means that bearing magnets thatco-rotate with the rotor are provided, which assume the stabilizingand/or centering function for the rotor.

According to a further embodiment, the bearing magnets of the rotor arearranged on the side of the rotor facing away from the inlet and/or thebearing magnets are arranged on the side facing the inlet. Depending onwhether the rotor has an axial, semi-axial or radial design and/ordepending on the flow conditions, maximum flexibility in the design ofthe blood pump is ensured.

According to a further embodiment, motor coils are provided in thestator of the blood pump and rotor magnets are provided in the rotor,wherein the motor coils are arranged on the side of the rotor facing theinlet and/or on the side of the rotor facing away from the inlet. Thisensures maximum flexibility in the configuration of the blood pump.

According to a further embodiment, a mechanical bearing is arranged onthe side of the rotor facing the inlet and/or on the side of the rotorfacing away from the inlet. In this way, the rotor can be suspended in avariety of ways (preferably counter to the direction of flow of theblood entering through the inlet); however, other arrangements can alsobe provided, for example a system comprising two bearings, in whichclosing of the inlet by a rotor moving in the direction of the inlet isprevented.

According to a further refinement, the rotor is connected in the centralregion thereof to a mechanical bearing by way of struts. This isfavorable, for example, for configurations in which only one bearing isprovided, and this bearing is provided on the side of the rotor facingthe inlet (however, the mounting point can also be connected to therotor by way of struts on the outlet side).

According to a further embodiment, the blood pump comprises a stator,wherein this embodiment comprises bearing magnets (which are preferablyin contact with corresponding bearing magnets of the rotating rotor) inthe region of an axis of rotation of the rotor, and wherein the statormoreover comprises a stator element in the region of the axis ofrotation of the rotor, a cup of a mechanical bearing being arranged onthe tip of the stator element, and additionally rotor magnets of therotor (preferably in a support plate of the rotor) are arranged and/ormotor coils operatively connected to the rotor magnets are arranged inthe stator on the side of the rotor facing away from the inlet.

According to a further embodiment, the blood pump is designed as aradial pump comprising struts, wherein a cup of a mechanical bearingwhich is connected to struts of the rotor is arranged on an elevation ofthe stator in the region of the axis of rotation of the rotor, andbearing magnets are arranged on the stator side in the stator andbearing magnets arranged in the rotor are provided, preferably on theside of the rotor facing away from the inlet, and furthermore the rotoradditionally comprises rotor magnets on the side of the rotor facing theinlet, wherein these rotor magnets cooperate with motor coils in theregion of the inlet of the blood pump.

According to a further embodiment, the rotor is attracted by way ofpassive magnetic forces. As an alternative, it is also possible toprovide other configurations (see figures).

According to a further embodiment, the radial distance between at leastone rotor-side bearing magnet and at least one stator-side bearingmagnet is so small that secure support is also achieved with thesmallest possible volume of magnetically active material. Thefluid-permeable gap may be ≤50 μm, for example 100 μm (see also FIG. 4,reference numeral 13 in the present property right, for example). Thegap between the magnetically active parts can range between 500 μm and2000 μm, for example, such as 1000 μm, wherein this does not need to bean air gap; non-magnetic materials (appropriate plastic materials, forexample) can be present in this gap; for details or definitions,reference is made to the introductory part of the description of thepresent property right).

According to a further embodiment, the blood pump does not comprise aninlet guide vane connected upstream of the rotor. In embodiments inwhich only one bearing is provided, which supports the rotor counter tothe flow direction, it is possible to select such an embodiment (havinga simple design), in particular when the magnetic arrangement of thebearing magnets or a suitable interaction between the motor coils andthe magnets of the rotor providing the motive power is ensured insidethe blood pump.

According to a further embodiment, the bearing magnets of the rotor arefastened in cantilevers of the rotor which are fastened to the rotorbase body by way of struts, wherein these rotor-side bearing magnetsinteract with bearing magnets of the stator located radially outside thebearing magnets of the rotor so as to radially and/or axially stabilizethe rotor inside the blood pump.

According to a further refinement, the motor for providing the motivepower of the rotor is designed as a pancake motor.

A further aspect relates to the placement of permanent magnets in theblades of the rotor. This results in a reduction of the magnetic airgap. As a result, blades made of magnetic material and/or bladescomprising permanent magnets therein shall be considered to be disclosedfor all embodiments shown in the present patent application (regardlessof the type of bearing that is provided).

The invention will be described hereafter based on several drawings. Inthe drawings:

FIG. 1 shows a cross-section of a bearing having a magnet configurationthat enables a radial passive magnetic force and preloading in the axialdirection;

FIG. 2 shows an example of a blood pump that comprises an additionalmechanical bearing in the outlet-side region of the rotor;

FIG. 3 shows a further example of a blood pump that comprises ahydrodynamic bearing in the outlet-side region of the rotor;

FIG. 4 shows a further example of a blood pump that comprises amechanical bearing in the outlet-side region of the rotor. This pump hasthe magnets positioned in such a way that the pump does not require aninlet guide vane. So as to achieve the highest possible stiffness, therotor-side ring magnets are attached to the interacting magnets as closeto the pump tube as possible. The ring magnets are connected to therotor or attached to the blades by way of struts.

FIGS. 5 to 7 show examples of radial blood pumps that comprise amechanical bearing and are magnetically preloaded opposite to the inlet.In these embodiments as well, the ring magnet configuration can besimilar to that in FIG. 1. Again, force is removed from the mechanicalbearing in exemplary embodiments as a result of the axial thrust. Themechanical bearing is connected to a spindle in the center of the pumpby way of thin struts, for example, which rotate together with therotor. In examples, the motor is designed as a pancake motor, and themotor magnets are accommodated in the lower cover plate. The pump canalso be designed with an upper cover plate so as to be able to exertadditional, repelling magnetic forces that interact with the housing onthe rotor. Such a pump should always ensure mechanical contact of thecontact bearing.

FIG. 8 shows a further schematic illustration of a pump according to thepresent application.

FIG. 1 shows a blood pump 1 in the region of a bearing 3. The arrowsshown in FIG. 1 indicate the orientation of the layered magnets;however, this shall only be understood by way of example, withoutdefining a resulting magnetic force direction. In particular, it isapparent from FIG. 1 how a portion of a rotor 2 is held radially in aring of the bearing 3 by a radial passive magnetic force, and preloadingin a desired axial direction is achievable. Examples for the use of sucha bearing are shown in the following figures.

FIG. 2 shows such a blood pump 1, in which a rotor 2 is mounted. Forthis purpose, bearings 3 (according to FIG. 1, for example) held onrespective struts (inlet guide vane or diffuser) 5 are provided in theregion of the inlet 10 and of the outlet 11. A flow (which is to say afluid flow) in the direction of the arrow 6 is created by the rotationof the rotor. The rotor is driven by a motor, which is not shown here.

The blood pump 1 thus includes an inlet 10 and an outlet 11, wherein therotor 2 is designed for delivering fluid (in direction 6) from the inletto the outlet. The rotor 2 is suspended by radial passive magneticforces inside the blood pump 1 and axially is attracted (preloaded) inthe direction of the outlet 11 at least by way of passive magneticforces, so that the axial thrust of the rotor acts counter to the actingmagnetic preload during a fluid-delivering rotation of the rotor 2. Thismeans that the flow takes place from the inlet 10 to the outlet 11 indirection 6, and the axial thrust of the rotor acts in the oppositedirection.

FIG. 2 additionally shows a mechanical bearing in the outlet-side regionof the rotor, which is present in the form of a contact bearing 4(designed as a tip bearing here). This enables exact positioning orcentering of the rotor, for example at low speeds, with comparativelylittle friction. In the region of the tip bearing, a portion of therotor or abutting surfaces of the blood pump are made of hard materials(such as gemstones, for example ruby, sapphire, diamond, DLC orceramics) so as to further minimize the friction here and increase thedurability.

FIG. 3 shows an alternative design of a blood pump. Again, an axialinlet 10 is shown. Furthermore, an outlet chamber or an outlet 11 isshown, which enables blood to flow out tangentially/laterally. The rotor2 is suspended by radial magnetic forces in a bearing 3 (see FIG. 1) andis axially preloaded in one direction. The rotor is driven in acontact-free manner by a motor 8. Additionally, a catcher bearing 9 isshown, which prevents the rotor 2 from jamming or sliding out of theblood pump housing when the inlet 10 is suctioned on a cardiac wall.

FIG. 3 furthermore shows a hydrodynamic bearing 7 on the outlet-side endof the blood pump. This is a spiral groove bearing, for example, whichmakes contact with abutting regions of the housing of the blood pump,for example at low speeds (at which the hydrodynamic properties do notfully take effect yet). Ceramic and/or DLC materials are also providedin this region to reduce friction and/or to increase the service life.At the operating speed of the blood pump, the hydrodynamic bearing takeseffect (which is to say direct contact no longer exists). The additionalaxial thrust of the rotor supports the hydrodynamic bearing and reducesthe load thereon. The following features may also apply to the rotor ofFIG. 3:

A blood pump (1), comprising an inlet (10), an outlet (11) and a rotor(2) for delivering fluid from the inlet (10) to the outlet (11), whereinthe rotor (2) is suspended within the blood pump (1) by radial passivemagnetic forces and axially is attracted or repelled in one direction atleast by way of passive magnetic forces, preferably in such a way that,during a fluid-delivering rotation of the rotor (2), the axial thrust ofthe rotor acts counter to the magnetic attraction acting axially in thedirection of the outlet.

The present property right furthermore relates to the following aspects,some of which have already been briefly addressed above.

One aspect is to develop, for example, an axial (or semi-axial orradial) rotary blood pump (small control unit) that is preferablypassively supported, comprising no large surface-area hydrodynamicbearing.

This object is achieved, for example, in that an axial/semi-axial orradial pump is supported by radial passive magnetic forces (if necessaryusing a supporting hydrodynamic component), and that a passive magneticpreload in one direction is also present axially. The axial thrust,which is present anyhow and dependent on the pressure differential, actsin the opposite axial direction. With an ideal design of the pump andappropriate adaptation of the outlet housing/diffuser, positive axialthrust will always be present in human circulatory system, and the rotorcan thus levitate without the use of an additional bearing. The axialsupport is helped by a one-sided mechanical or hydrodynamic bearing.

An inlet-side mechanical catcher bearing for when the axial thrustbecomes too great (during suctioning on the cardiac tissue) can beensured by way of material combinations (ceramics, hard coating, such asDLC).

The magnetic axial preload can also be selected to be so strong thatcontact is made with the axial mechanical bearing even in the worst-casescenarios (suctioning).

The radial passive magnetic force and the preloading in an axialdirection can be achieved by way of the magnet configuration shown inFIG. 1, for example.

The axial preloading can also be implemented by additional attracting orrepelling magnets.

The following refinements of the present invention are possible, amongother things:

-   1. Radial support: Magnetically supported journal bearings having a    large gap (for example, ≤100 μm).    -   Axial support: passive magnetic (preloading in the direction of        the outlet) and mechanical bearing on the outlet side. The        mechanical bearing can take on axial, radial or other forms of        sliding bearings (see FIG. 2, for example). The axial thrust        generates forces in the direction of the inlet. If necessary:        mechanical (catcher) bearing in the direction of the inlet.-   2. Radial support: Magnetically supported sliding bearings having a    large gap (>100 μm).    -   Axial support: passive magnetic, axial thrust and, where        necessary, hydrodynamic bearing. The hydrodynamic bearing (see        FIG. 3) can be implemented in the form of a spiral groove        bearing or by ramps and the like on the rotor or on the housing.-   3. Blood pump that comprises a mechanical bearing in the outlet-side    region of the rotor. This pump has the magnets positioned in such a    way that the pump does not require an inlet guide vane. So as to    achieve the highest possible stiffness, the rotor-side ring magnets    are attached as close as possible to the pump tube with the    interacting magnets. The ring magnets are connected to the rotor or    attached to the blades by struts.-   4. Blood pumps that comprise a mechanical bearing and are    magnetically preloaded in the direction of the outlet. In this    design as well, the ring magnet configuration is the same as that    described above (FIG. 1). Again, force is removed from the    mechanical bearing as a result of the axial thrust. The mechanical    bearing is connected to a spindle in the center of the pump by way    of thin struts, which rotate together with the rotor. In the    embodiments, the motor is designed as a pancake motor, and the motor    magnets are accommodated in the lower cover plate. The pump can also    be designed with an upper cover plate so as to be able to exert    additional, repelling magnetic forces that interact with the housing    on the rotor. Such a pump must always ensure mechanical contact of    the contact bearing.

Hereafter, FIGS. 4 to 7 additionally will be described in detail.

FIG. 4 shows an example of an axial blood pump 1 comprising a rotor 2.The rotor comprises blading in the form of blades 14. The rotorcomprises rotor magnets, which are not shown in greater detail andcooperate with a motor or motor coils 8 of a stator of the blood pump 1.The rotor magnets can be accommodated in the blades 14; as analternative, these may also be provided further to the radial inside inthe rotor, wherein the efficiency of the motor may then be slightlylower.

The stator has a substantially tubular design, comprising an inlet 10and a non-axial outlet 11. A bearing 3, which is designed as a slidingbearing, such as an axial or radial bearing, is provided on the side ofthe rotor facing away from the inlet. The bearing is arranged in such away that the flow entering through the inlet 10 subjects the bearing topressure. The blades 14 are oriented in such a way that pressure reliefwith respect to the bearing 3 takes place during a delivering movementof the rotor 2. Bearing magnets of the rotor 15 and bearing magnets ofthe stator 16 are provided so as to additionally stabilize the rotorradially and axially inside the stator of the blood pump. The bearingmagnets of the rotor 15 are fastened to cantilevers of the rotor by wayof struts 12. The corresponding cantilevers in which the bearing magnets15 are accommodated can have a circular ring-shaped design, for example;it is also possible for individual satellites to be provided, which aredistributed across the circumference of the circle. Such cantilevers maybe provided on corresponding struts both on the inlet side and on theoutlet side. The advantage of this arrangement is that (regardless ofthe blading) good radial and axial stabilization of the rotor inside thestator can be achieved. For this purpose, it is favorable when a gap 13is as small as possible, for example 50 μm, but less than 200 μm,preferably less than 150 μm, and particularly preferably less than 100μm.

In the arrangement shown in FIG. 4, it is achieved by way of the struts12 (which are rod-shaped, for example, and allow liquid to pass through)that not only good stabilization of the rotor 2 is provided in theregion of the cantilevers or the bearing magnets 15/16, but alsorelatively unimpaired through-flow of fluid (preferably blood) ispossible despite the small gap widths 13.

FIG. 5 (FIG. 5a showing a side view, FIG. 5b showing a section B-B fromFIG. 5a , FIG. 5c showing a section C-C from FIG. 5a , and FIG. 5dshowing a scaled down perspective view of the overall pump comprising aninlet 10 and an outlet 11; the inlet 10 being designed for theattachment to a cannula or a blood vessel, which also applies to theoutlet 11) shows a fully implantable blood pump comprising anintracorporeal radial pump including magnets and a motor inside a pumphousing. An axial inlet and a radial outlet are provided in the housing.The rotor 2 is supported on a mechanical bearing 4, which is designed asa contact bearing and has a particularly low-friction design, whereinthe material pairing comprises ceramic materials and/or a hard coating,for example DLC. The portion of the rotor that is being supported isconnected to the remaining rotor by way of struts 12. The rotor isdesigned to be hollow in some regions, which is to say it comprisesoblique/radial delivery blades, which deliver fluid entering axiallythrough the inlet 10 radially to the outside. The rotor 2 has asubstantially disk-shaped design, wherein the bearing is arranged in thelower region and, in the region thereabove, the channels or bladesproviding the fluid delivery are provided, and above that (which is tosay in the direction of the inlet) the rotor magnets 18 are provided,which cooperate with motor coils 17 provided axially thereabove (whichis to say further in the direction of the inlet 10) for driving therotor 2 located in the stator. This has the advantage that preferablyfew moving elements are provided and only electromagnetic actuation ofthe rotor inside the housing of the blood pump takes place. This notonly requires low maintenance, but also has a simple configuration.

In addition, rotor-side bearing magnets 15 and stator-side bearingmagnets 16 are provided, which are provided to radially and axiallystabilize the rotor inside the housing of the blood pump. Again, thebearing is arranged in such a way that the rotor is pressed against thebearing 4 under fluid pressure and when the rotor is stopped, and thepressure on the bearing 4 is relieved when fluid is being deliveredthrough the rotor 2. It shall be pointed out again that the layereddesign of the rotor enables a clear and simple design, wherein rotormagnets 18 and rotor-side bearing magnets 15 are accommodated in a coverplate of the rotor and cooperate with corresponding stator-side elements(motor coils 17 or stator-side bearing magnets 16).

FIG. 6 (FIG. 6a showing a side view, FIG. 6b showing a section B-B fromFIG. 6a , FIG. 6c showing a section C-C from FIG. 6a , and FIG. 6dshowing a scaled down perspective view of the overall pump comprising aninlet 10 and an outlet 11; the inlet 10 being designed for theattachment to a cannula or a blood vessel, which also applies to theoutlet 11) shows a further embodiment in which again an axial inlet 10and a radial outlet 11 are shown. This is a semi-axial pump comprising acentral stator element, in which stator-side bearing magnets 16 areinstalled and on the tip of which the cup of a mechanical bearing 4 isseated. The motor coils 17 are located in the housing, which is to sayon the stator side in the blood pump 1; these cooperate with rotormagnets 18 accommodated in the lower portion of the rotor 2. Ifnecessary, this rotor 2 can also comprise an additional cover plate. Asa result, this is a blood pump 1 comprising a stator 19, wherein bearingmagnets of the stator are arranged in the region of an axis of rotationof the rotor 2, and wherein the stator 19 comprises a stator element inthe region of the axis of rotation of the rotor 2, a cup of a mechanicalbearing being arranged on the tip of the stator element, andadditionally rotor magnets 18 of the rotor are preferably arranged in asupport plate of the rotor 2 and/or motor coils 17 operatively connectedto the rotor magnets are arranged in the stator 19 on the side of therotor 2 facing away from the inlet 10.

FIG. 7 shows a further embodiment of a blood pump 1 in which an axialinlet 10 and a radial outlet 11 are provided. On the side facing theinlet, the rotor 2 comprises rotor magnets 18, which cooperate withmotor coils 17 in the housing of the blood pump 1 for the motive powerfor the rotor. Rotor-side bearing magnets 15 are attached on the side ofthe rotor facing away from the inlet, which cooperate with stator-sidebearing magnets 16 so as to radially and axially stabilize the rotorinside the blood pump. Additionally, a mechanical bearing 4 is provided,in which struts 12 that allow liquid to pass through in the directionfrom the inlet 10 to the outlet 11 are provided and enable additionalmechanical mounting or support of the rotor. This is a blood pump 1designed as a radial pump comprising struts 12, wherein a cup of amechanical bearing which cup is connected to struts 12 of the rotor 2 isarranged on an elevation of the stator 19 in the region of the axis ofrotation of the rotor 2, and bearing magnets 16 are arranged on thestator side in the stator 19 and rotor-side bearing magnets 15 arepreferably arranged on the side of the rotor 2 facing away from theinlet 10, and furthermore rotor magnets 18 are preferably arranged onthe side of the rotor 2 facing the inlet, which rotor magnets 18cooperate with motor coils 17 in the region of the inlet 10 of the bloodpump.

FIG. 8 shows another variant of a pump. For the sake of clarity, theinlet is not shown. The outside of the pump resembles the appearance ofthe pump illustrated in FIG. 5a or 6 a.

The pump 30 comprises a base body 32, which accommodates a motor stator34 comprising a stator winding 35 and a stator core 35 a, and moreoverincludes a rotor chamber 36. The motor stator 34 revolves around therotor chamber 36. The rotor chamber 36 moreover comprises an outlet (notshown), which essentially corresponds to one of the outlets from FIGS. 5and/or 6. An elevation 38, having a ball or a conical section of a ball40 arranged on the tip thereof, is located centrally in the rotorchamber 36. With respect to the ball, the arrangement thereof and thematerials thereof, reference is made to the EP application EP16191613.5, for example, which is hereby incorporated in its entirety inthe present application by reference.

A rotor 42, which includes a cup 44 corresponding to the ball 40 on thebottom side thereof, is arranged in the rotor chamber 36 so that therotor 42 is able to rotate on the ball 40 about the axis 46. The rotor42 itself is shaped so as to be able to rotate freely about the axis 46in the rotor chamber. The only connection between the rotor chamber 36and the rotor 42 is provided by the ball 40. A support or pivot bearingis formed between the rotor 42 and the ball 40.

The rotor 42 comprises a central body 48 and an annular body 50. The twobodies are non-rotatably connected to one another by way of a pluralityof struts 52. Permanent magnets 54 are arranged in the annular body,which are aligned so as to be able to set the rotor 42 in motion by wayof the motor stator 34. Axially aligned permanent magnets 56 and 58 arearranged in the central body 48 and in the elevation 38, respectively,which bring about an axially attracting force and axially preload thepivot bearing. This prevents the rotor 42 from being drawn upward in thefigure during the pumping process. Optionally, the permanent magnets 56and 58 furthermore form a passive radial bearing, which counteracts therotor 42 giving way radially.

On the bottom side of the annular body 50, the rotor 42 comprisesblading 60, which can be designed similarly to the blading illustratedin FIG. 5, for example. The rotor chamber 36 can comprise a bulge 62 atthe height of the blading so as to improve the transport of blood to theoutlet. The shown pump can have a very small height since the base body,due to the motor stator 34 revolving radially around the rotor chamber,essentially only has to have the height of the rotor chamber, inaddition to the corresponding wall thickness of the wall surrounding therotor chamber. While this increases the radial dimension of the basebody, the axial height can be considerably reduced and/or the size ofthe rotor chamber can be increased, so that the rotor, at lowrevolutions, is able to deliver a volume of blood that is comparable toa small rotor chamber, which in turn reduces the blood damage.

Tilting the rotor about the ball is stabilized by the interaction of theforces from the attracting magnetic bearing 56, 58 and the aligningpassive magnetic forces from the motor. An aligning torque acts betweenthe motor magnets and the motor stator due to the reluctance forces, oran aligning moment acts due to the magnetic forces of the magneticbearing.

The present invention relates to the following aspects, among otherthings:

-   1. A blood pump (1), comprising    -   an inlet (10),    -   an outlet (11) and    -   a rotor (2) for delivering fluid from the inlet (10) to the        outlet (11), wherein the rotor (2) is suspended within the blood        pump (1) by radial passive magnetic forces and axially is        attracted in the direction of the outlet (11) at least by way of        passive magnetic forces, preferably in such a way that, during a        fluid-delivering rotation of the rotor (2), the axial thrust of        the rotor acts counter to the magnetic attraction acting axially        in the direction of the outlet.-   2. The blood pump according to aspect 1, characterized in that the    rotor (2) is attracted purely by way of passive axial magnetic    forces.-   3. The blood pump according to any one of the preceding aspects,    characterized in that an electromagnetic and/or electrodynamic    device acting on the rotor (2) is provided so as to enhance the    axial thrust.-   4. The blood pump according to any one of the preceding aspects,    characterized in that the rotor (2) is additionally supported by a    mechanical bearing (4), in particular for axial support.-   5. The blood pump according to aspect 4, characterized in that the    mechanical bearing (4) is arranged in the inlet-side and/or    outlet-side region of the rotor (2).-   6. The blood pump according to either aspect 4 or 5, characterized    in that the mechanical bearing (4) is designed as a contact bearing,    and in particular as a tip or ball bearing.-   7. The blood pump according to any one of the preceding aspects,    characterized in that the rotor (2) is additionally supported by a    hydrodynamic bearing (7), in particular for axial support.-   8. The blood pump according to aspect 7, characterized in that the    hydrodynamic bearing (7) is arranged in the outlet-side region of    the rotor (2).-   9. The blood pump according to either aspect 7 or 8, characterized    in that the hydrodynamic bearing (7) is designed as a spiral groove    bearing.-   10. The blood pump according to any one of the preceding aspects,    characterized in that an additional bearing, and in particular a    catcher bearing, is provided for limiting the axial rotor movement    in the direction of the inlet (10).-   11. The blood pump according to any one of aspects 4 to 10,    characterized in that the rotor (2) and/or abutting parts of the    blood pump are reinforced in the region of at least one additional    bearing, in particular with ceramic materials and/or DLC.

The bearing technology shown in the present property right can representa platform of small, passive rotary blood pumps having highhemocompatibility and comprising a small control unit and the like.

LIST OF REFERENCE NUMERALS

(excerpt, applicable to all embodiments in the drawings unless denotedotherwise)

-   1 blood pump-   2 rotor-   3 bearing-   4 contact bearing-   5 struts (extending from the pump tube)-   6 direction of an arrow-   7 hydrodynamic bearing/spiral groove bearing-   8 motor-   9 catcher bearing-   10 inlet-   11 outlet-   12 struts (on the rotor)-   13 gap-   14 blades of the rotor-   15 bearing magnets, rotor-   16 bearing magnets, stator-   17 motor coil-   18 rotor magnets-   19 stator-   30 pump-   32 base body-   34 motor stator-   35, 35 a stator winding or core-   36 rotor chamber-   38 elevation-   40 ball-   42 rotor-   44 cup-   46 axis-   48 central body-   50 annular body-   52 struts-   54, 56, 58 permanent magnets-   60 blading-   62 bulge

1. A blood pump, comprising an inlet, an outlet, and a rotor fordelivering fluid from the inlet to the outlet, wherein the rotor issuspended within the blood pump by radial passive magnetic forces toaxially attract or repel in one direction at least by way of passivemagnetic forces, so that during a fluid-delivering rotation of therotor, axial thrust of the rotor acts counter to magnetic attractionacting axially in a direction of the outlet.